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20 August 2019, Volume 40 Issue 08

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International Literature Characteristics and Hotspots Evolution of Agricultural under Climate Change：Bibliometrics Analysis Based on CiteSpace V

HUANG Cheng-fang，LI Ning，LIU Li，LIU Yuan，ZHANG Zheng-tao，Chen Xi

2019, 40(08):  477-488.  doi:10.3969/j.issn.1000-6362.2019.08.001

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This research was designed to explore the evolution of the research hotspots in agriculture under climate change, and provide some references for the development and innovation in this field. We used CiteSpace V, a network visualization analysis software, to analyze 11430 literatures, with keywords of "climate change" and "agriculture", included in the Web of Science from 1985 to 2018. The results showed that since 1985, the number of annual total papers in agriculture has been in an upward trend. The countries and regions with rapid economic development, such as the United States, the United Kingdom, China, Germany and Australia, have paid much attention to the research and exploration in agriculture. In addition, the most literatures were published in Climatic Change and Science. The Chinese Academy of Sciences, Wageningen University and some other well-known institutions were all committed to this field. Hot words in this field included "influence", "adaptability", "management", "model" and "food safety". In 2007, the research hotspots changed from the evaluation of future crop yields and its influence factors under climate change to agricultural adaptation, climate-smart agriculture and conservation agriculture. We concluded that the climate-smart agriculture will be the innovation and development of agriculture in the near future.

Seasonal Variation about the Occurrence Frequency of Different Types of Precipitation and Their Relative Contribution over Northwest China

SUN Yue，GAO Ji-qing，YANG Xiao-guang

2019, 40(08):  489-501.  doi:10.3969/j.issn.1000-6362.2019.08.002

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Based on the long-term daily precipitation data measured at 124 meteorological station in Northwest China from 1951 to 2015, the difference of the contribution rate of precipitation amount and precipitation days among different precipitation grades in each season were investigated and the variation characteristics of spatial and temporal were clarified in this study. How the changes of precipitation amount (days) in different seasons affect annual precipitation amount (days) and how the changes of precipitation amount (days) in different grades affect seasonal precipitation amount (days) were also figured out. The results showed that: (1) annual precipitation days decreased significantly with an averaging downward trend of 0.1 days per decade in Northwest China from 1951 to 2015. Significant difference was shown in both precipitation days and its temporal variation among different observation stations. (2) The annual precipitation amount in Northwest China also increased significantly from 1951 to 2015, with an average increasing trend of 3.9mm per decade. (3) Strong seasonal variations were shown in precipitation amount and days, with the most in summer and the least in winter. The contribution rate of summer precipitation amount and days in each province was 50%-63% and 35%-48%. The precipitation amount was similar in spring and autumn. In each season, the light and moderate rain was mainly, which accumulative contribution rate of precipitation days was above 90%. The rainstorm only occurred in summer, which contribution rate was less than 1%. (4) The variation of precipitation amount(days) in summer and autumn was the most important reason for the change of annual precipitation amount(days), and the change of light and moderate rain was the most important reason for the change of total seasonal precipitation amount(days). The precipitation in spring and winter was not dominant in the annual precipitation, and the heavy and rainstorm were not dominant in the current season (annual) precipitation, so their effect were not obvious.

Effects of Water Stress on Growth and Physiological Properties of Millet Seedlings

HAN Zhi-ping, ZHANG Hai-xia, ZHANG Xun, LIANG Yan-hua

2019, 40(08):  502-511.  doi:10.3969/j.issn.1000-6362.2019.08.003

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In order to study the effects of water stress on the growth, membrane lipid peroxidation and osmotic adjustment of broom corn millet seedlings, the experiment was conducted 5 treatments: severe drought, slight drought, normal irrigation control, slight flooding and severe flooding. ‘Jinshu No. 8’ millet as material was grown in sand culture and irrigated with nutrient solution, and indicators including the morphological indicators, biomass, water content of plant, and the membrane permeability, the contents of photosynthetic pigments, MDA, AsA, proline, soluble sugar and soluble protein in leaves were determined on 20th day after treatment. The results showed that the millet seedling grew best under normal irrigation condition, with the largest values of plant height, stem diameter, nodule number, leaf number, maximum leaf area, fresh mass and dry mass of root, stem and leaf, and panicle. All morphological indicators and biomasses were obviously decreased under drought and flooding treatments, and the extent of decrease under severe drought and severe flooding were more obvious than those under slight drought and slight flooding. The water contents of root, stem and leaf, panicle were clearly decreased under drought, but showed different tendency under flooding treatments. The contents of photosynthetic pigments were significantly decreased under drought, while relatively stable under flooding. The membrane permeability, the contents of MDA, AsA and proline were obviously increased under drought and flooding, and the extents of increase under severe drought and severe flooding were more obvious than those under slight drought and slight flooding. The soluble sugar content was clearly increased under drought and was clearly decreased under flooding, the soluble protein content was significantly reduced under drought and was relatively stable under flooding. The research illustrated that the drought and flooding caused the peroxidation injury to the millet seedlings, and the contents of antioxidants and osmotic adjusting materials were increased. But the increase of antioxidants could not completely eliminate the peroxidation injury caused by stress. In addition, the photosynthetic ability was decreased under stress, which caused the inhibition of the growth of millet seedlings. Under the experimental condition, drought stress caused more serious damage to millet seedlings than flooding.

Low Temperature and Low Irradiation Affected the Metabolism of Low-Molecular- Weight Organic Acids and Nutrients Uptake in Tomato Seedling Root

LI Yu-shan, LI Ping, YANG Zai-qiang, WANG Fu

2019, 40(08):  512-522.  doi:10.3969/j.issn.1000-6362.2019.08.004

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Combined low temperature and low irradiation(LTLI) conditions seriously affect the yield and quality of tomato, the present study aimed to clarify the underlying mechanisms through investigating the changes of organic acids metabolism and nutrients uptake in tomato root. A pot experiment in artificially controlled environments was conducted to study the dynamic changes of root activity, nitrogen(N), phosphorus(P), and potassium(K) uptake by the root, dry weights of the root and shoot, and the secretion of low-molecular-weight organic acids(LMWOAs) by the root, under different LTLI conditions (maximum/minimum temperature: 12/2℃, 14/4℃, 16/6℃, 18/8℃; weak irradiation: 200, 400μmol·m-2·s-1). Results showed that the LTLI strongly inhibited the root activity, net absorption of N, P and K, and dry weights of the root and shoot, and the effects were enhanced with the decrease of temperature. Under the condition of 12/2℃ and 200μmol·m?2·s?1, the root activities were 7.70%-22.1% of the control, net absorption of N, P and K in the root were 3.75%-18.1%, 1.28%-27.1%, and 19.1%-35.5% of the control, respectively, dry weights of the root and shoot were 23.4%-55.9% and 42.6%-66.5% of the control, respectively. The LTLI also inhibited the secretion of LMWOAs and increased the soil pH, oxalic acid was the main acid which decreased most obviously. This study indicates that the inhibition of the LTLI on the growth of tomato seedling was related to the decrease of root activity, secretion of oxalic acid, and the nutrients uptake. Therefore, suitable application of oxalic acid or complex fertilizer (including N, P, K) at the initial stage of the LTLI occurrence, may enhance the resistance ability of tomato seedling to the LTLI.

Establishment of a Critical Nitrogen Dilution Model for Grapes and Nitrogen Nutrition Diagnosis under Different Water Conditions

LI Jia-shuai, YANG Zai-qiang, LI Yong-xiu, JIANG Meng-yuan, ZHAO He-li, WEI Ting-ting, ZHANG Xu-ran

2019, 40(08):  523-533.  doi:10.3969/j.issn.1000-6362.2019.08.005

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In this paper, a two-factor pot experiment was carried out in the Venlo-type greenhouse, using the annual grape of "Hongti" variety as experimental material. There were four irrigation levels and four nitrogen application levels in the two-factor pot experiment. Four irrigation levels were normal irrigation (W1, 70%-80% of the maximum water holding capacity in the field), slight drought stress (W2, 60%-70%), moderate drought stress (W3, 50%-60%) and extra severe drought tress (W4, 30%-40%). And four nitrogen application levels were 1.5 times normal recommended nitrogen application rate(N1, 25.5gplant-1), normal recommended nitrogen application rate(N2, 17gplant-1), 0.5 times normal recommended nitrogen application rate(N3, 8.5gplant-1) and no nitrogen application(N4, 0gplant-1). The nitrogen concentration in the plant and the aboveground biomass of the plant were observed every 10 days. The minimum nitrogen concentration corresponding to the maximum biomass obtained by grape plants under different water conditions in a certain period is called Nitrogen critical concentration (Nc), it can be used to construct the model of nitrogen critical concentration dilution curve of grape, which can further establish Nitrogen uptake model (Nupt) and Nitrogen Nutrition Index model (NNI) for quantitative diagnosis of nitrogen nutrition status of grapes under different water conditions.The results showed: there was a power function relationship between the nitrogen critical concentration and aboveground biomass of grape plants, which embodied as the nitrogen critical concentration, nitrogen uptake and aboveground biomass of grape plants all increased as the irrigation amount increasing. As nitrogen application increased, the biomass of grape plants under treatments of W1 and W2 increased, while that under W3 and W4, increased first and then decreased. Under the same water condition, the nitrogen concentration increased with the increase of nitrogen application and decreased with the progress of grapes growth. The established Nupt and NNI models can be used to effectively diagnose the deficiency of nitrogen nutrients in plants.

Frost Automatic Identification Model Based on Logistic Regression

ZHU Hua-liang, WEN Hua-yang, HUA Lian-sheng, JIN Su-wen, CHEN Jing-jing

2019, 40(08):  534-542.  doi:10.3969/j.issn.1000-6362.2019.08.006

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Using the threshold-based methods of meteorological elements on frost-free days, the quality-controlled daily observation data were firstly established, using the observed data from 23 typical meteorological stations in Anhui province from 2003 to 2017. The automatic identification models of frost based on Logistic regression were constructed for each meteorological station in Anhui province, and the performance of the frost identification model was evaluated. The results showed that: (1) the daily frost-free phenomena could be correctly determined for each station in Anhui province by the thresholds of meteorological elements such as temperature, wind speed and precipitation amount. (2)Temperature, humidity and wind speed were selected as the identification elements in the frost identification models for all meteorological stations. The observation time of model elements mostly occurred at the stage from 4：00 to 8：00. (3)The accuracy rate, hit rate, miss rate, empty judgement rate and TS score of Logistic regression model based on independent sample test were 89.0%, 91.6%, 8.4%, 15.8% and 78.2%, respectively. This indicates that the frost recognition model established by Logistic regression has good ability to identify frost in Anhui province. (4) Compared with Bayes discriminant model, it was found that the frost identification model based on Logistic regression had higher accuracy rate and TS score, and lower empty judgement rate. Therefore, the proposed Logistic regression model can be applied to the automatic identification of frost in the future.